The story
After Lewis Carroll's Alice's Adventures in Wonderland (1865; often known as Alice in Wonderland), in which the protagonist changes size after consuming a potion and a cake.
Etymology from Wiktionary, CC BY-SA 4.0.
Alice in Wonderland syndrome
Today it means: A disorienting neurological condition involving micropsia, macropsia, or size distortion of other sensory modalities. Full definition →